/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <net/if.h>
#include <net/pfkeyv2.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <libdscp.h>

/*
 * Define the file containing the configured DSCP interface name
 */
#define DSCP_CONFIGFILE         "/var/run/dscp.ifname"

/*
 * Forward declarations
 */
static int get_ifname(char *);
static int convert_ipv6(struct sockaddr_in6 *, uint32_t *);
static int convert_ipv4(struct sockaddr_in *,
    struct sockaddr_in6 *, int *);

/*
 * dscpBind()
 *
 *      Properly bind a socket to the local DSCP address.
 *      Optionally bind it to a specific port.
 */
int
dscpBind(int domain_id, int sockfd, int port)
{
        int                     len;
        int                     len6;
        int                     error;
        struct sockaddr_in      addr;
        struct sockaddr_in6     addr6;

        /* Check arguments */
        if ((sockfd < 0) || (port >= IPPORT_RESERVED)) {
                return (DSCP_ERROR_INVALID);
        }

        /* Get the local DSCP address used to communicate with the SP */
        error = dscpAddr(domain_id, DSCP_ADDR_LOCAL,
            (struct sockaddr *)&addr, &len);

        if (error != DSCP_OK) {
                return (error);
        }

        /*
         * If the caller specified a port, then update the socket address
         * to also specify the same port.
         */
        if (port != 0) {
                addr.sin_port = htons(port);
        }

        /*
         * Bind the socket.
         *
         * EINVAL means it is already bound.
         * EAFNOSUPPORT means try again using IPv6.
         */
        if (bind(sockfd, (struct sockaddr *)&addr, len) < 0) {

                if (errno == EINVAL) {
                        return (DSCP_ERROR_ALREADY);
                }

                if (errno != EAFNOSUPPORT) {
                        return (DSCP_ERROR);
                }

                if (convert_ipv4(&addr, &addr6, &len6) < 0) {
                        return (DSCP_ERROR);
                }

                if (bind(sockfd, (struct sockaddr *)&addr6, len6) < 0) {
                        if (errno == EINVAL) {
                                return (DSCP_ERROR_ALREADY);
                        }
                        return (DSCP_ERROR);
                }
        }

        return (DSCP_OK);
}

/*
 * dscpSecure()
 *
 *      Enable DSCP security mechanisms on a socket.
 *
 *      DSCP uses the IPSec AH (Authentication Headers) protocol with
 *      the SHA-1 algorithm.
 */
/*ARGSUSED*/
int
dscpSecure(int domain_id, int sockfd)
{
        ipsec_req_t     opt;

        /* Check arguments */
        if (sockfd < 0) {
                return (DSCP_ERROR_INVALID);
        }

        /*
         * Construct a socket option argument that specifies the protocols
         * and algorithms required for DSCP's use of IPSec.
         */
        (void) memset(&opt, 0, sizeof (opt));
        opt.ipsr_ah_req = IPSEC_PREF_REQUIRED;
        opt.ipsr_esp_req = IPSEC_PREF_NEVER;
        opt.ipsr_self_encap_req = IPSEC_PREF_NEVER;
        opt.ipsr_auth_alg = SADB_AALG_MD5HMAC;

        /*
         * Set the socket option that enables IPSec usage upon the socket,
         * using the socket option argument constructed above.
         */
        if (setsockopt(sockfd, IPPROTO_IP, IP_SEC_OPT, (const char *)&opt,
            sizeof (opt)) < 0) {
                return (DSCP_ERROR);
        }

        return (DSCP_OK);
}

/*
 * dscpAuth()
 *
 *      Test whether a connection should be accepted or refused.
 *      The address of the connection request is compared against
 *      the remote address of the specified DSCP link.
 */
/*ARGSUSED*/
int
dscpAuth(int domain_id, struct sockaddr *saddr, int len)
{
        int                     dlen;
        struct sockaddr         daddr;
        struct sockaddr_in      *sin;
        struct sockaddr_in6     *sin6;
        uint32_t                spaddr;
        uint32_t                reqaddr;

        /* Check arguments */
        if (saddr == NULL) {
                return (DSCP_ERROR_INVALID);
        }

        /*
         * Get the remote IP address associated with the SP.
         */
        if (dscpAddr(0, DSCP_ADDR_REMOTE, &daddr, &dlen) != DSCP_OK) {
                return (DSCP_ERROR_DB);
        }

        /*
         * Convert the request's address to a 32-bit integer.
         *
         * This may require a conversion if the caller is
         * using an IPv6 socket.
         */
        switch (saddr->sa_family) {
        case AF_INET:
                /* LINTED E_BAD_PTR_CAST_ALIGN */
                sin = (struct sockaddr_in *)saddr;
                reqaddr = ntohl(*((uint32_t *)&(sin->sin_addr)));
                break;
        case AF_INET6:
                /* LINTED E_BAD_PTR_CAST_ALIGN */
                sin6 = (struct sockaddr_in6 *)saddr;
                if (convert_ipv6(sin6, &reqaddr) < 0) {
                        return (DSCP_ERROR);
                }
                break;
        default:
                return (DSCP_ERROR);
        }

        /*
         * Convert the SP's address to a 32-bit integer.
         */
        /* LINTED E_BAD_PTR_CAST_ALIGN */
        sin = (struct sockaddr_in *)&daddr;
        spaddr = ntohl(*((uint32_t *)&(sin->sin_addr)));

        /*
         * Compare the addresses.  Reject if they don't match.
         */
        if (reqaddr != spaddr) {
                return (DSCP_ERROR_REJECT);
        }

        return (DSCP_OK);
}

/*
 * dscpAddr()
 *
 *      Get the addresses associated with a specific DSCP link.
 */
/*ARGSUSED*/
int
dscpAddr(int domain_id, int which, struct sockaddr *saddr, int *lenp)
{
        int                     error;
        int                     sockfd;
        uint64_t                flags;
        char                    ifname[LIFNAMSIZ];
        struct lifreq           lifr;

        /* Check arguments */
        if (((saddr == NULL) || (lenp == NULL)) ||
            ((which != DSCP_ADDR_LOCAL) && (which != DSCP_ADDR_REMOTE))) {
                return (DSCP_ERROR_INVALID);
        }

        /*
         * Get the DSCP interface name.
         */
        if (get_ifname(ifname) != 0) {
                return (DSCP_ERROR_DB);
        }

        /*
         * Open a socket.
         */
        if ((sockfd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) {
                return (DSCP_ERROR_DB);
        }

        /*
         * Get the interface flags.
         */
        (void) memset(&lifr, 0, sizeof (lifr));
        (void) strncpy(lifr.lifr_name, ifname, sizeof (lifr.lifr_name));
        if (ioctl(sockfd, SIOCGLIFFLAGS, (char *)&lifr) < 0) {
                (void) close(sockfd);
                return (DSCP_ERROR_DB);
        }
        flags = lifr.lifr_flags;

        /*
         * The interface must be a PPP link using IPv4.
         */
        if (((flags & IFF_IPV4) == 0) ||
            ((flags & IFF_POINTOPOINT) == 0)) {
                (void) close(sockfd);
                return (DSCP_ERROR_DB);
        }

        /*
         * Get the local or remote address, depending upon 'which'.
         */
        (void) strncpy(lifr.lifr_name, ifname, sizeof (lifr.lifr_name));
        if (which == DSCP_ADDR_LOCAL) {
                error = ioctl(sockfd, SIOCGLIFADDR, (char *)&lifr);
        } else {
                error = ioctl(sockfd, SIOCGLIFDSTADDR, (char *)&lifr);
        }
        if (error < 0) {
                (void) close(sockfd);
                return (DSCP_ERROR_DB);
        }

        /*
         * Copy the sockaddr value back to the caller.
         */
        (void) memset(saddr, 0, sizeof (struct sockaddr));
        (void) memcpy(saddr, &lifr.lifr_addr, sizeof (struct sockaddr_in));
        *lenp = sizeof (struct sockaddr_in);

        (void) close(sockfd);
        return (DSCP_OK);
}

/*
 * dscpIdent()
 *
 *      Determine the domain of origin associated with a sockaddr.
 *      (Map a sockaddr to a domain ID.)
 *
 *      In the Solaris version, the remote socket address should always
 *      be the SP.  A call to dscpAuth() is used to confirm this, and
 *      then DSCP_IDENT_SP is returned as a special domain ID.
 */
int
dscpIdent(struct sockaddr *saddr, int len, int *domainp)
{
        int     error;

        /* Check arguments */
        if ((saddr == NULL) || (domainp == NULL)) {
                return (DSCP_ERROR_INVALID);
        }

        /* Confirm that the address is the SP */
        error = dscpAuth(0, saddr, len);
        if (error != DSCP_OK) {
                if (error == DSCP_ERROR_REJECT) {
                        return (DSCP_ERROR);
                }
                return (error);
        }

        *domainp = DSCP_IDENT_SP;
        return (DSCP_OK);
}

/*
 * get_ifname()
 *
 *      Retrieve the interface name used by DSCP.
 *      It should be available from a file in /var/run.
 *
 *      Returns: 0 upon success, -1 upon failure.
 */
static int
get_ifname(char *ifname)
{
        int             i;
        int             fd;
        int             len;
        int             size;
        int             count;
        int             end;
        int             begin;
        struct stat     stbuf;

        /*
         * Initialize the interface name.
         */
        (void) memset(ifname, 0, LIFNAMSIZ);

        /*
         * Test for a a valid configuration file.
         */
        if ((stat(DSCP_CONFIGFILE, &stbuf) < 0) ||
            (S_ISREG(stbuf.st_mode) == 0) ||
            (stbuf.st_size > LIFNAMSIZ)) {
                return (-1);
        }

        /*
         * Open the configuration file and read its contents
         */

        if ((fd = open(DSCP_CONFIGFILE, O_RDONLY)) < 0) {
                return (-1);
        }

        count = 0;
        size = stbuf.st_size;
        do {
                i = read(fd, &ifname[count], size - count);
                if (i <= 0) {
                        (void) close(fd);
                        return (-1);
                }
                count += i;
        } while (count < size);

        (void) close(fd);

        /*
         * Analyze the interface name that was just read,
         * and clean it up as necessary.  The result should
         * be a simple NULL terminated string such as "sppp0"
         * with no extra whitespace or other characters.
         */

        /* Detect the beginning of the interface name */
        for (begin = -1, i = 0; i < size; i++) {
                if (isalnum(ifname[i]) != 0) {
                        begin = i;
                        break;
                }
        }

        /* Fail if no such beginning was found */
        if (begin < 0) {
                return (-1);
        }

        /* Detect the end of the interface name */
        for (end = size - 1, i = begin; i < size; i++) {
                if (isalnum(ifname[i]) == 0) {
                        end = i;
                        break;
                }
        }

        /* Compute the length of the name */
        len = end - begin;

        /* Remove leading whitespace */
        if (begin > 0) {
                (void) memmove(ifname, &ifname[begin], len);
        }

        /* Clear out any remaining garbage */
        if (len < size) {
                (void) memset(&ifname[len], 0, size - len);
        }

        return (0);
}

/*
 * convert_ipv6()
 *
 *      Converts an IPv6 socket address into an equivalent IPv4
 *      address.  The conversion is to a 32-bit integer because
 *      that is sufficient for how libdscp uses IPv4 addresses.
 *
 *      The IPv4 address is additionally converted from network
 *      byte order to host byte order.
 *
 *      Returns:        0 upon success, with 'addrp' updated.
 *                      -1 upon failure, with 'addrp' undefined.
 */
static int
convert_ipv6(struct sockaddr_in6 *addr6, uint32_t *addrp)
{
        uint32_t                addr;
        char                    *ipv4str;
        char                    ipv6str[INET6_ADDRSTRLEN];

        /*
         * Convert the IPv6 address into a string.
         */
        if (inet_ntop(AF_INET6, &addr6->sin6_addr, ipv6str,
            sizeof (ipv6str)) == NULL) {
                return (-1);
        }

        /*
         * Use the IPv6 string to construct an IPv4 string.
         */
        if ((ipv4str = strrchr(ipv6str, ':')) != NULL) {
                ipv4str++;
        } else {
                return (-1);
        }

        /*
         * Convert the IPv4 string into a 32-bit integer.
         */
        if (inet_pton(AF_INET, ipv4str, &addr) <= 0) {
                return (-1);
        }

        *addrp = ntohl(addr);
        return (0);
}

/*
 * convert_ipv4()
 *
 *      Convert an IPv4 socket address into an equivalent IPv6 address.
 *
 *      Returns:        0 upon success, with 'addr6' and 'lenp' updated.
 *                      -1 upon failure, with 'addr6' and 'lenp' undefined.
 */
static int
convert_ipv4(struct sockaddr_in *addr, struct sockaddr_in6 *addr6, int *lenp)
{
        int                     len;
        uint32_t                ipv4addr;
        char                    ipv4str[INET_ADDRSTRLEN];
        char                    ipv6str[INET6_ADDRSTRLEN];

        /*
         * Convert the IPv4 socket address into a string.
         */
        ipv4addr = *((uint32_t *)&(addr->sin_addr));
        if (inet_ntop(AF_INET, &ipv4addr, ipv4str, sizeof (ipv4str)) == NULL) {
                return (-1);
        }

        /*
         * Use the IPv4 string to construct an IPv6 string.
         */
        len = snprintf(ipv6str, INET6_ADDRSTRLEN, "::ffff:%s", ipv4str);
        if (len >= INET6_ADDRSTRLEN) {
                return (-1);
        }

        /*
         * Convert the IPv6 string to an IPv6 socket address.
         */
        (void) memset(addr6, 0, sizeof (*addr6));
        addr6->sin6_family = AF_INET6;
        addr6->sin6_port = addr->sin_port;
        if (inet_pton(AF_INET6, ipv6str, &addr6->sin6_addr) <= 0) {
                return (-1);
        }

        *lenp = sizeof (struct sockaddr_in6);

        return (0);
}